Bearings: definition, classification, types and purpose

The functionality of bearings is very wide. They are indispensable for ensuring reliable fixation, easy rotation or rolling, and reducing friction between two parts of the structure. The simple invention is one of the leading in the industry and is used everywhere. The performance and wear resistance of the machine largely depends on its quality. The variety of such assemblies is as great as their purpose. What is a bearing, what types exist and their classification according to their main characteristics, we will tell you in this article and show photographs.

What is a support

At its core, the part is the basis of the assembly unit. Its main function is to provide reliable support and support a certain moving part of the structure. How rigid such fixation will be depends on the device, material and many other factors.

Fixing the position in space allows for rotational movements and rolling with minimal resistance. This way the load is transferred from the moving part of the unit to others, maintaining wear resistance.

What are the types and types of bearings?

All assemblies can be classified according to their operating principle. Two main groups are devices that provide rocking and sliding. They are the ones most often used in mechanical engineering. The first can be represented by ball and roller devices.

Magnetic structures deserve special attention. The principle of their operation is different from the others, and they are used less often. In addition, due to their functional features, they must be accompanied by spare units.

Bearings are parts that help to obtain maximum efficiency from a machine, maintaining its performance without special repairs and maintenance.

Sliding supports

This group of parts allows you to slide freely when two contacting surfaces rub against each other. In this case, various lubricants are used - oils, water, chemicals, graphite and some gases. Structurally, such devices can be either integral or collapsible. Manufactured complete with bushing and connecting part.

Devices by rolling type

Such units are made in the form of two rings, bodies that provide a rocking effect, and a separator. They are manufactured in accordance with established standards, which allows them to be used in most cars, complex equipment and aircraft.

Ball bearings

Functionally, they are part of a group of node parts that operate on the rolling principle. Ball bodies are located on the surface of the outer rings of the parts. During operation, they create a small friction moment, which means they practically do not limit the rotation speed.

Roller bearings

They are part of the rolling group, but they are based on balls replaced by rollers. This allows them to withstand much greater loads. This performance is highly valued in the design of industrial machines and railway construction.

Magnetic supports

They work on the principle of levitation of attraction, ensuring complete non-contact of two adjacent parts. They can be used in aggressive environments, but are not yet as common as the types already listed. If you do not back up such a design with another, more traditional one, you can lose the entire car overnight.

Factors to consider

The roller wheel bearing has a low permissible ring rotation speed. This can be seen when comparing devices with cylindrical rollers. When compared with spherical roller bearings, they are found to be approximately the same. Tapered bearings can always be separated into two parts and then reassembled into their original position. You can install two rings separately, then they are conventionally divided into internal and external.

The bearing, the price of which is often no more than 300 rubles, is used in helical gears operating on a mechanical principle. They are usually attached to the hubs of vehicles, both passenger and commercial. Sometimes these elements are involved in the design of railway axle boxes.

Plain bearings

The main task of such parts is to ensure free friction between two mating sections. They can be used for both moving and fixed surfaces, which significantly increases the functionality of the application.

Types of sliding support units

This type of node part can be detachable or integral. The first consists of two liners installed in the half-holes of the base and cover. They may have a thick or thin wall relative to the outer diameter. The thickness is determined by the material used. For example, thin-walled ones are most often made of light low-carbon steel. The one-piece design involves a special assembly, in which a hole is drilled in the part into which a metal sleeve is pressed.

Varieties

The most common classification is based on the ability to absorb load in direction. In this case, devices are divided into 3 groups:

• • Radial – accepting perpendicular load from the axis.
• • Persistent – ​​take on the entire load.
• • Radial-thrust – combine the properties of both.

There are several other options for separating nodes, but they are rather secondary.

Sliding bearing standards

The quality of workmanship of parts, the material used in the work and other production conditions are described in the Interstate ISO standard and GOST. The first one complies with international requirements valid in 165 countries of the world. The second is internal to the Russian Federation. All components presented undergo mandatory certification for compliance with the stated rules.

Plain bearing lubrication

This type is designed to provide free friction between two parts of the structure. For normal operation, one of 4 types of lubricants is used:

• • Liquid – various synthetic and mineral oil fluids for metal supports or water for non-metallic ones.
• • Plastic – made from base oil and thickener.
• • Solid – used in dry and boundary contact conditions. The materials most often chosen are graphite and molybdenum disulfide.
• • Gaseous – required when the structure operates under light load, but in hot conditions and at high speeds.

Advantages and disadvantages

Among the advantages are their high reliability when operating at high speed and their small size. As for the disadvantages, we note the need to constantly adjust the amount of lubricant, reduced efficiency and production from expensive materials.

Where are the devices used?

The scope of application of the devices is wide. Quite often they are used in high-speed equipment, steam and turbine units, in equipment for navigation systems and other precision instruments.

Series by outer diameter

This parameter is indicated by the third digit from the right. With the same design and inner diameter, bearings can differ in outer diameter and width. Depending on this, the standards determine their series. The outer diameter in the marking is indicated by the third number from the right, and the width is indicated by the seventh number from the right. The designations according to the standards are currently accepted as follows:

• 1 - series is especially light;
• 2 - light;
• 3 - average;
• 4 - heavy;
• 5 - light wide;
• 6 - medium wide.

The bearing, marked 6-6180306, belongs to the medium wide series.

Rolling bearings

These nodal supports consist of two rings, but in addition to them, at the base there are always bodies that provide rocking and a separator. On the inner surface there are gutters that act as tracks. In rare cases, the separator may be absent, but then the level of resistance becomes higher.

Purpose

The main purpose of the devices is to serve as a stop for rotating parts of mechanisms. This is why they are more popular than slip knots. They are used in electrical machines and other structures where it is necessary to ensure wear resistance and long-term operation without lubrication.

Classification

Such parts can be divided according to several criteria, but the most common is the division according to the shape of the bodies and the acceptance of the load. The first group includes the previously mentioned ball and roller joint bearings. The second is similar to the division of sliding bearings by type of load.

Specifications

To select a particular device, you need to take into account several basic parameters. The most important are:

• • Overall dimensions established by the ISO standard.
• • Basic and complete designation, including an alphanumeric code indicating type, size and design.
• • Tolerances corresponding to classes.
• • Clearance, the total distance that one ring can move relative to another.

It offers to select the necessary part in accordance with all the characteristics. Our range includes a wide variety of bearings suitable for any mechanism.

Advantages and disadvantages

The main advantages are: low cost and mass production. If necessary, they can be easily replaced, which means installation and maintenance of the machines will become more convenient. Lubricants are used in small quantities, which allows you to avoid spending a lot of time on caring for mechanisms.

The disadvantages include:

• • Excessive sensitivity to vibration and shock loads.
• • Excessive heat and risk of destruction at high speeds.
• • Large radial dimensions.
• • Noise during operation.

Despite significant shortcomings, today they are the most popular all over the world.

Notes

1. [www.snr.com.ru/e/about_bearings/about_bearing.htm Information about bearings: What are bearings and their main types]
2. [www.krugosvet.ru/enc/nauka_i_tehnika/tehnologiya_i_promyshlennost/PODSHIPNIK.html BEARING | Online Encyclopedia Around the World]
3. [podshipneek.ru/podshipniki-nsk/rabochie-harakteristiki-podshipnikov.html Bearing performance characteristics | Bearings]
4. [podshipnikcentr.ru/smazka/smazka-dlya-podshipnikov.html Grease for bearings]. podshipnikcentr.ru. Retrieved March 23, 2016.
5. Skoybeda A. T., Kuzmin A. V., Makeichik N. N.
   Machine parts and design fundamentals: Textbook / Ed. ed. A. T. Skoybeda. - Mn.: Higher School, 2000. - P. 426. - 584 p. — 3000 copies. — ISBN 985-06-0081-0.

Ball bearing

This type of part uses balls that move freely along tracks as the body that provides rocking. Used for rotating structures that do not require strong friction between two moving parts.

Description

The unit consists of 2 rings made of steel. Together they form a kind of “bed” for ball bodies. In this case, the inner part of the device is fixed on the shaft, and the outer part is fixed on the support. Despite their simplicity of design, they are widely used in industry.

Varieties

What types of bearings with ball bodies there are can be guessed based on the general classification. Like most rolling parts, they are divided into: radial, thrust and with 4-point contact. The peculiarity of the latter is the ability to perceive load in two axis directions or simultaneous combined and axial load on one side.

Application

Different types are used in electric motors and various household appliances, in woodworking machines, in medical equipment, machine spindles and pumps. Ball bearings with 4-point contact are widely used in gearboxes.

Marking

When manufacturing products such as bearings, standards must be observed. And of course, manufacturers of such devices, according to regulations, must provide consumers with all the necessary information about them. The marking of bearings produced in Russia usually consists of three parts:

• main designation;
• additional characters on the right and left.

For clarity, here is an example of bearing marking:

• 6-180306US17SH.

Here the main part consists of six digits. The additional sign on the left (“6”) indicates the accuracy class of the product. The marking on the right US17SH stands for this:

• U is the degree of roughness;
• C17 - type of lubricant;
• Ш - degree of noise.

The main numbers indicate:

• types of bearings;
• series by outer diameter and width;
• internal diameters;
• design features.

Roller bearings and their varieties

In their structure, these supports are similar to the previous type, but instead of balls, a body shaped like a roller is used here. This way the device can take on a heavier load.

Description

The design is designed in such a way that it shows resistance to radial pressure, but at the same time the speed of the roller along the track is in no way inferior to ball bearings. The only thing you should pay attention to is the axial load. To make the device more resistant to it, the rolling element is replaced with a conical one.

Kinds

This type is classified according to the body used. Separately distinguished:

• • Cylindrical.
• • Conical.
• • Needle-shaped.
• • Spherical.

Application

Roller bearings are often used in pumps, high-power gearboxes, the railway industry and the automotive industry. All types of roller bearings are presented in pictures on the website mirpl.ru.

Links

• [www.pdsar.biz/information Directories with information about bearings]

Magnetic support units

Unlike others, this device works on the principle of magnetic levitation. This ensures complete non-contact between the two parts of the structure.

Description

The elements are made in such a way that the shaft floats without contacting other surfaces. To ensure reliable operation, a large number of sensors are provided to coordinate all movements.

Varieties

There are two groups: active and passive. The first composition includes the bearing itself and the electronic system. The work of the second group is based on the presence of permanent magnets. They are less stable than in the case of an electronic control system, and therefore are used much less frequently.

Application

Such devices can be used in gas centrifuges, turbomolecular pumps, in various electromagnetic suspensions, in cryogenic technology, in vacuum devices and other complex mechanisms.

Advantages and disadvantages

As advantages, we highlight the wear resistance of parts and the possibility of their use in an aggressive environment, including in space. The disadvantages are manifested in the instability of the magnetic field, due to which traditional rolling or sliding devices are additionally built into the mechanism.

Literature

• Anuriev V.I.
  Handbook of mechanical engineering designer: In 3 volumes / Ed. I. N. Zhestkova. — 8th ed., revised. and additional.. - M.: Mashinostroenie, 2001. - T. 2. - 912 p. — ISBN 5-217-02964-1 (5-217-02962-5), BBK 34.42ya2, UDC 621.001.66 (035).
• Nichiporchik S.N., Korzhentsevsky M.I., Kalachev V.F. et al.
  Chapter 13. Sliding bearings // Machine parts in examples and problems: [Text. allowance] / Under general. ed. S. N. Nichiporchik. — 2nd ed. — Mn.: Vysh. school, 1981. - 432 p. — ISBN BBK 34.44 I 73, UDC 621.81 (075.8).
• Lelikov O.P.
  Fundamentals of calculation and design of parts and machine components. Lecture notes for the course “Machine parts”. - M.: Mechanical Engineering, 2002. - 440 p. — ISBN 5-217-03077-1, UDC 621.81.001.66, BBK 34.42.
• Iosilevich G. B.
  Machine parts: A textbook for mechanical engineering students. specialist. universities - M.: Mechanical Engineering, 1988. - 368 p. — ISBN 5-217-00217-4, UDC 62-2(075.8), BBK 34.44.

Other types

Let's consider several more types of nodal supports, differing in some functional features.

Tapered bearings

This is a type of roller, but the body here is made in the form of a cone and is installed on the track at an angle. They cope well with both radial and axial loads.

Self-aligning double row

They differ from others in their low friction, which makes them possible to operate at the highest speeds. Installed on a conical or cylindrical shaft journal.

Needle type

Here, a thin and long roller acts as a rolling body. The elements look more compact, but at the same time provide greater performance and reliability, and are economical to use.

Thrust ball bearings

The main purpose is the perception of axial loads. It belongs to the group of ball joints, so its appearance completely corresponds to them.

Spherical

Provide low friction. The design simultaneously includes two rows of rollers arranged symmetrically.

Heat resistant

Designed to work in hot conditions. They are distinguished by reliability and ease of operation.

Floating Nodal Support

Allows the shaft to move linearly. Bears only radial load. Easily adjustable and easy to operate.

Speed ​​devices

Provides normal rolling at high speeds. They are distinguished by excellent quality and wear resistance.

Spindle

Has good load capacity. Often used in fans, powerful pumps and machine tools, as it works well at high speeds.

High precision

They have high performance characteristics, due to which they are often used in aircraft construction, astronautics and the military industry.

Closed

Equipped with seals that close open space. This allows for increased wear resistance in difficult conditions.

Flange bearings

The built-in flange increases the reliability of the fastening so that the part can withstand heavy loads.

Supporting

Perceive gravity along the axis of rotation. The scope of application is very limited, therefore it is less common than other options.

Linear Motion Devices

They have high performance qualities with minimal friction.

size table

The catalog of ball bearings by size is intended to help in finding the optimal technical solution. Selection of bearings by size, the table of which contains invaluable information about such product parameters as the diameter of the inner (outer) ring, product width, etc., ensures not only the correct choice of components, but also a quick selection of analogues. Thus, it can be argued that the use of a rolling bearing sizing chart is a fairly important factor in ensuring a smooth workflow.

And finally, it is necessary to consider another important point regarding the service life of bearings. There are several factors that directly affect the lifespan of these products:

1. Protection from the negative influence of the external environment.
2. Fatigue failure of the metal used to manufacture the elements of the assembly and subsequent “crumbling”.
3. Hardness and degree of processing of the movable structure.
4. Use of the types and quantities of lubricants specified by the manufacturer.

Modern grades of steel, combined with high quality workmanship, are able to provide ball bearings with the opportunity to increase the nominal life declared by the manufacturer. The only conditions for such an extension are monitoring of contact loads and compliance with maintenance standards.